Table saw fences provide a straight working edge or face on a saw work table spaced in a selected position from a circular saw blade to guide a workpiece as it is pushed into cutting engagement with the blade, thus producing a sawn piece of predetermined width. It is important, of course, that the working face of the fence be as parallel as possible to the chord line of the segment of the saw blade projecting above the work table.
Prior art table saw fences include straight elongated fence elements slidable only at one end along a track fixed to the front edge of the work table, as disclosed for example in U.S. Pat. Nos. 4,206,910 and 4,600,184. However, with the remote end of the fence toward the rear of the table beyond the blade left unrestrained, inevitable play between the sliding parts of the fence element and the track at the front edge of the table may cause the unrestrained rear end of the fence to wobble ever so slightly, thus departing from the true parallelism desired between the fence working face and the chord of the blade segment.
This problem is addressed in other prior art fence designs by slidably mounting both the front and the rear ends of the fence on respective tracks on the front and rear edges of the table. The result is a doubling of the parts required for the slidable mounting. Another disadvantage in double track forms of fence is that it is difficult to insure that the pair of tracks are mounted exactly parallel to one another and remain that way. If they are not parallel either the fence attempting to slide on the non-parallel tracks will bind or play must intentionally be provided in the sliding parts to prevent binding, and that again introduces the possibility of wobble and non-parallelism between the working face of the fence and the saw blade segment chord. Double track forms of fences are described in the aforementioned U.S. Pat. No. 4,600,184.
Fence designs of the prior art have not contemplated joining together the fence and "track" in one T-shaped unit and then moving the track back and forth in a single fixed guide. This would avoid the problem of double guides at opposite ends of the fence and would allow the single guide to be placed on the table itself aligned over the saw blade axis that there would be no unrestrained fence end remote from the slidable mounting. Prior art fence designs also fail to take advantage of the technology of adjustable V-guide wheels and tracks for precise linear motion.